#!/usr/bin/env python3
"""Reconstruct EgoCoT-Bench processed clips from locally obtained source media.

This script does not download, upload, or redistribute third-party media. Users
must provide source videos obtained from the original dataset providers.
"""

from __future__ import annotations

import argparse
import csv
from pathlib import Path


VIDEO_EXTENSIONS = (".mp4", ".mov", ".mkv", ".avi", ".webm")


def find_source_video(source_root: Path, source_dataset: str, source_video_id: str) -> Path:
    dataset_root = source_root / source_dataset
    candidates = []
    for root in (dataset_root, source_root):
        for ext in VIDEO_EXTENSIONS:
            candidates.append(root / f"{source_video_id}{ext}")
    for candidate in candidates:
        if candidate.exists():
            return candidate
    raise FileNotFoundError(
        f"Could not find source video for {source_dataset}/{source_video_id}. "
        f"Looked under {dataset_root} and {source_root}."
    )


def reconstruct_with_opencv(row: dict[str, str], input_video: Path, output_path: Path) -> None:
    try:
        import cv2
    except ImportError as exc:
        raise RuntimeError(
            "OpenCV is required for reconstruction. Install opencv-python."
        ) from exc

    fps = float(row.get("fps", "4"))
    width = int(row["target_width"])
    height = int(row["target_height"])
    cap = cv2.VideoCapture(str(input_video))
    if not cap.isOpened():
        raise RuntimeError(f"Failed to open source video: {input_video}")

    try:
        raw_fps = cap.get(cv2.CAP_PROP_FPS)
        frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
        duration = frame_count / raw_fps if raw_fps > 0 else 0
        target_frame_count = int(duration * fps)
        if target_frame_count <= 0:
            raise RuntimeError(f"Invalid target frame count for {input_video}")

        fourcc = cv2.VideoWriter_fourcc(*"mp4v")
        writer = cv2.VideoWriter(str(output_path), fourcc, fps, (width, height))
        if not writer.isOpened():
            raise RuntimeError(f"Failed to open output video writer: {output_path}")
        try:
            for i in range(target_frame_count):
                target_time = i / fps
                raw_frame_idx = int(round(target_time * raw_fps))
                if raw_frame_idx >= frame_count:
                    raw_frame_idx = frame_count - 1
                cap.set(cv2.CAP_PROP_POS_FRAMES, raw_frame_idx)
                success, frame = cap.read()
                if not success:
                    continue
                if frame.shape[1] != width or frame.shape[0] != height:
                    frame = cv2.resize(frame, (width, height))
                writer.write(frame)
        finally:
            writer.release()
    finally:
        cap.release()


def reconstruct_row(
    row: dict[str, str],
    source_root: Path,
    output_root: Path,
    dry_run: bool,
) -> tuple[str, str | None]:
    if row.get("source_dataset") == "Self-recorded":
        return "self_recorded", None
    rel_output = Path(row["expected_local_output_path"])
    if rel_output.is_absolute():
        raise ValueError(f"expected_local_output_path must be relative: {rel_output}")
    output_path = output_root / rel_output
    if output_path.exists():
        return "existing", None

    try:
        input_video = find_source_video(source_root, row["source_dataset"], row["source_video_id"])
    except FileNotFoundError:
        return "missing_source", f"{row.get('source_dataset')}/{row.get('source_video_id')}"

    output_path.parent.mkdir(parents=True, exist_ok=True)

    if not dry_run:
        reconstruct_with_opencv(row, input_video, output_path)
    return ("dry_run" if dry_run else "reconstructed"), None


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--manifest", default="manifests/media_reconstruction.csv")
    parser.add_argument("--source-root", required=True)
    parser.add_argument("--output-root", default="media_reconstructed")
    parser.add_argument("--dry-run", action="store_true")
    args = parser.parse_args()

    source_root = Path(args.source_root)
    output_root = Path(args.output_root)
    seen_outputs: set[str] = set()
    missing_sources: set[str] = set()
    counts = {
        "reconstructed": 0,
        "dry_run": 0,
        "existing": 0,
        "missing_source": 0,
        "self_recorded": 0,
        "duplicate": 0,
    }
    with Path(args.manifest).open(newline="", encoding="utf-8") as handle:
        for row in csv.DictReader(handle):
            output_key = row.get("expected_local_output_path", "")
            if output_key in seen_outputs:
                counts["duplicate"] += 1
                continue
            seen_outputs.add(output_key)
            status, missing_source = reconstruct_row(row, source_root, output_root, args.dry_run)
            counts[status] += 1
            if missing_source:
                missing_sources.add(missing_source)
    if missing_sources:
        print("Missing source videos:")
        for source in sorted(missing_sources):
            print(source)
    else:
        print("No missing source videos.")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())